KR20160097139A - A process for producing foam mouldings - Google Patents

Abstract

The present invention relates to a method of manufacturing a foamed molded article. The method according to the present invention comprises the steps of: a) providing a first amount of expandable foam particles; b) providing a second amount of expandable foam particles; c) producing a physical mixture based on the first and second amounts of expandable foam particles; and d) introducing the mixture from step c) into a mold and sintering the mixture under a pressure and heat. A chemical origin of the first amount of expandable foam particles is different from a chemical origin of the second amount of expandable foam particles. Furthermore, according to the method, a coating exists on the mixture before the mixture is injected into the mold. Accordingly, it is possible to produce a biology-based foamed molded article having acceptable mechanical properties.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a process for producing foamed molded articles,

The present invention relates to a foamed molding as well as a method for producing an expanded molded article.

The manufacture of the foamed molded part according to the international patent application WO2011133035 (corresponding to EP 2 561 013) in the name of the present applicant is based on a method in which the pre-expansible starting material is confined in a so-called vapor chamber and further expansion of the polystyrene particles takes place It happens by using. During this possible preliminary announcement, the raw EPS is processed, for example under the influence of steam, whereby the expanded granules of polystyrene are expanded. After such treatment, such prefoamed EPS can be further developed in subsequent treatments, and this subsequent treatment is to aged, especially stored, the thus treated granules for 4 to 48 hours. The final foam may be produced by treating the different starting materials in a vapor mold or a vapor-treated mold. During this process, the particles will adhere to each other and a compressed structure is formed. Before the vapor chamber or mold is filled with a combination of starting materials, a mixture of desired EPS materials is first produced, and the desired composition is summarized in the dependent claims. After the desired mixture is injected together, the starting material is thereby taken from the silo in particular. This type of vessel is filled, and then steam is introduced through it. Due to the high temperature of the steam, the blowing agent will attempt to expand and the EPS particles will fuse together due to the vapor, which will also heat them above the glass transition temperature due to the limited room of this type. The mold used for this purpose is formed with small openings through which the foaming agent and steam can pass.

According to Dutch patent NL 1033719 in the name of the present applicant, a process for the production of foamed molded parts is disclosed in which the particles of polylactic acid are sprayed onto the particles of polylactic acid in a pressure vessel at a pressure of 20 bar for 5 hours, Is impregnated. The polylactic acid particles thus obtained are then pre-expanded or pre-expanded by application of warm air (having a temperature of about 90 DEG C) for a period of one minute. The prefoamed polylactic acid particles have a density of approximately 60 g / l. Finally, the prefoamed polylactic acid particles are coated in a fluidized bed reactor, and after the coating of the prefoamed polylactic acid particles, the particles are subjected to a foaming agent, i. E., By treatment in a pressure vessel for 20 to 20 minutes, CO2 is once again impregnated. Once again the polylactic acid particles impregnated contain approximately 7% by mass of CO2. The polylactic acid particles once again impregnated are then added to the industrial production unit for the foamed molded part where further expansion and fusion from the prefoamed polylactic acid particles takes place by application of the vapor resulting in a density of 60 g / To obtain a foamed molded part with the foam. According to the Dutch patent NL 1033719 it is also possible to arrange the polylactic acid particles after extrusion in a fluidized bed reactor so as to provide the coating, i. E. By application of a solution of 50% by weight of polyvinyl acetate. After coating, the thus coated polylactic acid particles are impregnated with a foaming agent, i.e., CO 2, by treatment in a pressure vessel at a pressure of 20 bar for a period of 20 minutes. The impregnated polylactic acid particles contained about 7% by weight of CO2 by weight and then added to the industrial production unit for the foamed molded part where the foamed molded part with a density of 60 g / Expansion and fusion of the polylactic acid particles takes place in order to obtain. In both methods, impregnation of the blowing agent is an essential step.

EP 1 731 552 relates to a heat insulating foam material formed of an expandable styrene polymer consisting of pigment-containing and pigment-free styrene polymers.

WO2014 / 027888 (entitled " Applicant ") relates to a particulate expandable polymer containing a carbon-based material which can be processed into a flame retardant foam with a fine cell structure and low density and with an increased adiabatic value to improve the insulation value , Wherein the polymeric particles contain carbon having a particle size of less than 1 [mu] m as a material to increase the adiabatic value.

WO2014 / 157538 relates to a molded article of a composite resin comprising 100 parts by mass of an ethylene-vinyl acetate copolymer and 100 to 400 parts by mass of a polystyrene resin.

EP 0 732 357 relates to a process for the preparation of flame retarded polystyrene bead foams containing recycled polystyrene beads foam comprising the steps of coating the pulverized recycled polystyrenes with at least one flame retardant and applying the coated pieces to freshly prepared prefoamed polystyrene beads And fusing the mixture to give a molding.

US 2009/234035 relates to a method of making a foamed structure comprising providing at least one alkenyl aromatic polymer such as polystyrene and a copolymer thereof and a high impact polystyrene and a copolymer thereof; Providing at least one bio-based or biodegradable polymer; Providing at least one formulation compatibilizer, such as maleated SEBS, SEBS, styrene-maleic anhydride copolymer, and styrene-methyl methacrylate copolymer; Combining at least one alkenyl aromatic polymer, at least one bio-based or biodegradable polymer, and at least one formulation compatibilizer to form a blend; Extruding the formulation to form an extrudate; And expanding the extrudate to produce a foamed structure; Thermoforming the foamed structure to produce a thermoformed article. The bio-based or biodegradable polymer may be selected from the group consisting of polylactic acid and its copolymers, polyhydroxyalkanoates and copolymers thereof, and polybutylene succinate or copolymers thereof, polycaprolactone, polyvinyl alcohol and its copolymers, , Cellulosic polymers, and soy-based polymers.

DE 203 15 226 relates to an adiabatic foam material formed of an expandable styrene polymer particle, i.e., 10 to 90% by weight of colored styrene polymer particles and 90 to 10% by weight of pigment-free styrene polymer particles, -Containing styrene polymer particles are selected from carbon black, metal oxides, metal powders, color pigments and graphite, and the pigment-containing styrene polymer particles contain graphite particles in a homogeneous distribution.

WO2012 / 151596 relates to an expandable polymer or polymer granule in a polymer blend comprising cellulose acetate butyrate (CAB) and a styrene polymer, wherein at least one additional compatible polymer in the polymer blend, for example a polyurethane Or polylactic acid, wherein the cellulose acetate butyrate (CAB) and styrene together account for more than 80% by weight of the total mass of the polymer blend.

Particle-based expandable polystyrene (EPS) is used not only as a packaging material, but also as a structural element, for example as a panel in the housing industry. Specific properties are particularly required for such panels in terms of heat insulation, acoustic barrier and fire resistance (flame retardancy).

Over the last several years, interest in polylactic acid or PLA as a reproducible biologically degradable material has grown tremendously for a wide range of applications. BACKGROUND OF THE INVENTION In the development of foamed molded products based on expanded or foamed polylactic acid concerns, there is also a growing interest in recycling in connection with the increasing concern for environmental and recycling issues and the ever-increasing volume of waste. It is often claimed in the literature that polylactic acid is not recyclable and causes problems if it is involved in the process chain of another polymer, especially in the form of contaminants.

Foamed molded parts based on granular expandable polystyrene (EPS) and methods of making the same are disclosed in EP 1 486 530, US 6,465,533, EP 1 587 860, CA 2 171 413, GB 2 449 353, It is known per se from the application WO 2009/155066, EP 0 235 831, JP 2 222 435 and US 2010/099782.

EPS, also called expandable polystyrene, is a characteristic white plastic foam, consisting of about 98% air and about 2% polystyrene. This material is also known as air-pop, polystyrene or Styrofoam. EPS has a variety of uses such as packaging materials, horticultural dishes or fish box materials, and insulating materials for construction and installation.

PLA, also called polylactic acid, is a polymer of lactic acid molecules. Lactic acid is a substance released during various biological processes, such as fermentation of carbohydrates. PLA has already been synthesized in the laboratory 200 years ago, but has only found its way to industrial use for decades. Polylactic acid is a collective term used for polymers based on polylactic acid monomers, wherein the structure of the polylactic acid may vary from fully amorphous to semi-crystalline or crystalline depending on the composition. Polylactic acid may be produced from dairy products or corn, for example.

Lactic acid is a monomer that constitutes polylactic acid, and this monomer occurs in two stereoisomers, namely L-lactic acid and D-lactic acid. Such polylactic acid contains a predetermined proportion of L-lactic acid monomer and a predetermined proportion of D-lactic acid monomer. The ratio between the L-lactic acid monomer and the D-lactic acid monomer in the polylactic acid determines its properties. This is also known as the D value or the D-content, which indicates the proportion of D-lactic acid monomer in the polylactic acid. Currently commercially available polylactic acid has an L: D ratio of 100: 0 to 75:25; I. E., 0 to 25%, or 0 to 0.25. When the polylactic acid contains more than about 12% of D-lactic acid, it can not be crystallized anymore and is therefore completely amorphous. If the D-content is approximately 5%, it is referred to as semi-crystalline polylactic acid after processing. The crystallinity of the polylactic acid can be determined by differential scanning calorimetry (DSC). The term "semi-crystalline" is understood to mean that the polymer is arranged in its polymer structure by crystallization. Therefore, it can be said that the lower the D-content, the higher the degree of crystallization of the polylactic acid. The D-content is usually determined using known methods, such as the so-called R-lactate crystallization method using gas-liquid chromatography (GLC) after complete hydrolysis of the polymer. Another standard method is a crystal through optical rotation (measured in chloroform using a Jasco DIP-140 polarimeter at a wavelength of 589 nm).

In the production of molded articles based on particulate expandable polylactic acid, it is of utmost importance that the fusing between individual particles is sufficient to obtain a product that will not decompose into individual particles under some load. This process condition is also very important. From the viewpoint of the limited thermal stability of polylactic acid as compared to petrochemical or so-called oil based polymers, it is very important that good fusion is realized under mild process conditions.

With respect to bio-based materials, it can be said that there are essentially two fundamental reasons for the transfer from crude oil derivatives to biologically and renewable raw materials. The first reason is the expected decrease in fossil fuel abatement and oil stock (long-term continuity of supply), and the second reason is climate change. Climate change is considered to be the main challenge of society in the coming decade. Uncontrolled emissions of greenhouse gases have resulted in an increase in the average temperature of the Earth, and could lead to additional consequences affecting lifestyle in many parts of the world. The use of renewable resources reduces this effect and has significant environmental benefits.

The LCA study, screened mutually by Akzo Nobel Sustainable Systems, showed that bio based polymers such as EPLA foams (BioFoam, the assignee's trade name), etc., And 40 to 50% lower CO ₂ release.

At this time, the price of EPLA is higher than EPS, for example, i) the raw material cost per kg of PLA is higher than that of EPS, ii) the specific gravity of the molded foam is 20 g / l And 30 g / l for the PLA foam, compared to that of the foam, and iii) the additional processing equipment required to introduce the blowing agent into the mold.

One aspect of the present invention is to provide a method of making a bio-based foamed molded article having acceptable mechanical properties.

Another aspect of the present invention is to provide a method of making a bio-based foamed molded article, wherein standard process equipment for making foamed molded articles can be used.

Another aspect of the present invention is to provide a method for producing a bio-based foamed molded article which results in a foamed article having high temperature resistance.

Thus, the present invention relates to a method for producing an expanded molded article,

a) providing a first amount of expandable expanded particles;

b) providing a second amount of expandable expanded particles;

c) preparing a physical mixture based on said first and second amounts of expandable expanded particles; And

d) introducing the mixture of step c) into a mold and sintering under pressure and heat, wherein the chemical origin of the expandable expandable particles of the first quantity is different from the chemical origin of the expanded particles of the second quantity And the method further comprises the presence of a coating in the mixture prior to introducing the mixture into the mold.

The first amount of expandable expanded particles is preferably an oil-based polymer, that is, an oil-based polymer such as polystyrene (PS), polyphenylene oxide (PPO), polypropylene (PP), polyethylene (PE), polyethylene terephthalate Urethane (TPU) and combinations thereof, in particular PS / PE and PS / PPO blends.

The second amount of expandable expanded particles is preferably selected from the group consisting of bio-based polymers such as polylactic acid (PLA), polybutyrate adipate terephthalate (PBAT), polyhydroxyalkanoate (PHA), polyhydroxybutyrate PHB), celluloses, starches and combinations thereof, in particular PLA / starch blends and PLA / PBAT blends.

In certain embodiments, additional components may be added, such as conventional processing aids, for example, flame retardants, agents that increase the insulation value, flow agents, release agents, anti-agglomeration agents, And may or may not be premixed. However, the use of additional foaming agents is preferably excluded.

The second amount of expandable expanded particles is present in the range of 2 to 50% by weight, especially 5 to 20% by weight, preferably 10 to 15% by weight, based on the total weight of the foamed article obtained after step d) desirable.

The present inventors have found that it is desirable to apply, i.e., coat, the coating, for good adhesion between the bio-based polymer and the oil based polymer. In the first embodiment, the first amount of the expandable expanded particle is provided with a coating. In the second embodiment, the second amount of the expandable expanded particle is provided with a coating. According to another embodiment, a coating is provided on a physical mixture based on the first and second amounts of expandable expanded particles.

For sintering purposes according to step d), it is preferable to inject steam into the mold. In another embodiment of step d), hot air is injected into the mold.

In embodiments where a PLA / PBAT formulation is used, the amount of PBAT calculated relative to the total weight of the PLA / PBAT formulation is less than 75 wt%, preferably less than 50 wt%, more preferably less than 25 wt%. We have found that the greater the amount of PBAT in the PLA / PBAT blend, the worse the encapsulation of the bio-based polymer in the oil based polymer.

The density of the second expandable expanded particles is preferably in the range of 7 to 40 kg / m 3.

The density of the first expandable expanded particles is preferably in the range of 8 to 45 kg / m 3.

According to a preferred embodiment of the present invention, the first amount of expandable expanded particles is EPS, and the second amount of expandable expanded particles is EPLA.

EPLA has a preferred range of 20 to 100%, particularly a crystallinity in the range of 30 to 40%.

EPLA is a copolymer of PLA with a preferred D-content of 2 to 10%, especially 3 to 7%.

As mentioned above, it is preferred to apply the coating before the sintering of step d) is carried out, wherein the coating is preferably a polyurethane, a polyvinyl acetate, a polyvinyl acetate-based polymer, a polyvinyl alcohol, a polycaprolactone , Polyesters, polyester amides, protein-based materials, polysaccharides, natural waxes or greases and acrylates or a combination of one or more of these.

The amount of coating is preferably from 0.5 to 15% by weight, based on the weight of the expandable expanded particles in the second amount in the mixture prepared in step c).

The particle size of both the first amount of expandable expanded particles and the second amount of expandable expanded particles is preferably in the range of 0.5 to 5 mm, preferably 0.5 to 3 mm.

The sintering according to step d) can be carried out when the pressure is in the range of 0.5 to 30 kg / cm < 2 >.

In the method of producing the foamed article of the present invention in which the mixture of step c) is introduced into the mold and sintered under pressure and heat therein, the introduction of further blowing agent is excluded. A preferred embodiment of the application of the coating will result in good adhesion between the oil based polymer and the bio based polymer. In addition, the method of producing the foamed article of the present invention as mentioned in steps a) to d) also excludes the application of an extruder.

The present invention also relates to a foamed article obtained after carrying out the method of the present invention.

The composition of the foamed molding is preferably based on a sintered physical mixture of a first amount of expandable expanded particles and a second amount of expanded particles and the chemical origin of the first amount of expandable expanded particles is based on the There is a coating between the first and second amounts of expandable foam particles. The first amount of expandable expanded particles and the second amount of expanded particles are described above.

Preferred embodiments of the foamed article according to the present invention include EPS and EPLA, wherein the EPLA is preferably 3 to 50 wt%, especially 5 to 20 wt%, more preferably 5 to 20 wt%, based on the total weight of the foamed article Is present in the range of 10 to 15% by weight.

According to another embodiment, it is possible to inject a mixture of the first amount of expandable expanded particles and the second amount of expanded particles into the cavity between the two walls of the building. In this embodiment, the coating must be present in a first amount of expandable expanded particles or a second amount of expanded particles. Once the cavity between the two walls of the building is filled with this mixture, the fusion of the two expanded particles will automatically be initiated to form the closed structure of the fused expanded particles. These structures have adiabatic, acoustic barrier and moisture barrier properties.

The present invention will be further illustrated by several drawings and experiments.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a photograph of a foamed article made according to the method of the present invention;
2 is another photograph of a foamed article produced according to the method of the present invention.

The present inventors have conducted several experiments. In these experiments, not only the amount of EPLA in the EPS was changed, but also the coating, the type of bio-based polymer, the% D in EPLA and the crystallinity of EPLA were also changed. Actual results are shown in Tables 1 and 2. The in-mold process conditions are a temperature of 105 DEG C, a residence time of 80 seconds, and the injection of steam.

Table 1 shows the raw materials and their properties. For example, Example 1 is derived from Styrex 1016R, a commercial oil-based polymer of the expandable polystyrene EPS type manufactured by Synbra Technology BV, and Biofoam (trademark) manufactured by Shinbraterinoligovivov Lt; RTI ID = 0.0 > 1% < / RTI > by weight of EPLA.

Table 2 shows the physical and visual properties of the final molding. Examples 1, 2, 3 and 4 demonstrate that the maximum amount of EPLA is about 5% by weight of EPLA. Its origin is recycled beads already molded in advance. Examples 5, 6 and 7 demonstrate that encapsulation of EPLA in EPS is not sufficient, with different types of EPLA provided with an amount of 5% by weight of an adiabatic enhancing additive such as graphite, graphene and activated carbon. The present inventors assume that this phenomenon is due to the physical disturbing effect of these additives on crystallization, indicating that this requires the use of low D content bio-based polymers. However, the present inventors do not wish to be bound by this description. Examples 8 and 9 were carried out with the addition of coatings, namely PVnapas 2501 (Wacker product), a PVAC based adhesive. These Examples 8 and 9 demonstrate some improvement in encapsulation of EPLA in EPS. Examples 10-15 were performed with other types of EPS, namely Neopor TM (EPS) from BASF and Epotal P100 ECO (TM) from BASF, a polyurethane based adhesive. Examples 10 to 15 clearly demonstrate that acceptable moldings can also be obtained in high amounts of EPLA, e.g. 30% by weight. Examples 16 to 20 were carried out with other types of bio-based polymers indicating that acceptable moldings can be obtained well. In embodiments, the amount of coating, if any, is about 8% by weight, based on the weight of the expandable expanded particles in the second amount in the final mixture.

In Fig. 1, the molding 10 comprises fused beads of EPS 1 and EPLA 2. Moldings 10 clearly represent individual starting expanded particles of EPS 1 and EPLA 2. EPLA expanded particles are fully encapsulated in the EPS matrix. The molded product 10 shown in Fig. 1 was produced in accordance with Example 13.

Figure 2 shows a molding 10 containing EPS 1 and EPLA 2 fused beads, but the encapsulation of EPLA 2 in the EPS matrix exhibits some drawbacks because the EPLA 2 particles are loosely surrounded by the EPS matrix. The inventors assume that this effect can be contributed by an insufficient coating amount in the mixture of starting materials. The moldings 10 shown in Fig. 2 were produced in accordance with Example 8.

The moldings thus produced can be used not only as packaging materials but also as components, for example as panels in the housing industry. Specific properties are particularly required for such panels in terms of insulation, acoustic barrier and fire resistance.

Claims (23)

A method for producing an expanded molded article,
a) providing a first amount of expandable expanded particles;
b) providing a second amount of expandable expanded particles;
c) preparing a physical mixture based on said first and second amounts of expandable expanded particles; And
d) introducing said mixture of step c) into a mold and sintering under pressure and heat,
Wherein the chemical origin of the first amount of expandable expanded particles is different from the chemical origin of the expandable expandable particles of the second amount and the method further comprises the step of pre- ≪ / RTI > The method of claim 1, wherein said coating is provided to said first amount of expandable expanded particles. The method of claim 1, wherein the coating is applied to the second amount of expandable expanded particles. The method of claim 1, wherein the coating is provided to the physical mixture based on the first and second amounts of expandable expanded particles. 5. A method according to any one of claims 1 to 4, wherein hot air is injected into the mold in step d). 6. A process according to any one of claims 1 to 5, wherein steam is injected into the mold in step d). 7. The method of any one of claims 1 to 6, wherein the first amount of the expandable expanded particles is an oil-based polymer, that is, one selected from the group consisting of polystyrene (PS), polyphenylene oxide (PPO), polypropylene PP), polyethylene (PE), polyethylene terephthalate (PET), thermoplastic polyurethane (TPU) and combinations thereof, especially PS / PE blends and PS / PPO blends. 7. The method of any one of claims 1 to 6, wherein the second amount of expandable expanded particles is a bio based polymer, i.e., polylactic acid (PLA), polybutyrate adipate terephthalate (PBAT) , Polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), cellulose, starch and combinations thereof, in particular PLA / starch blends and PLA / PBAT blends Way. 9. The method of claim 8 wherein in the PLA / PBAT formulation, the amount of PBAT calculated relative to the fill weight of the PLA / PBAT formulation is less than 75 wt%, preferably less than 50 wt%, more preferably less than 25 wt% A method for manufacturing an expanded molded article. The method according to any one of claims 1 to 6 and 8 to 9, wherein the density of the expandable expanded particles in the second amount is in the range of 7 to 40 kg / m 3. The method according to any one of claims 1 to 7, wherein the density of the first amount of expandable expanded particles is in the range of 8 to 45 kg / m 3. 12. A process according to any one of claims 1 to 11, wherein the second amount of expandable expanded particles is from 2 to 50% by weight, in particular from 5 to 20% by weight, based on the total weight of the foamed article obtained after step d) By weight, preferably 10 to 15% by weight, based on the total weight of the foam. 13. The method according to any one of claims 1 to 12, wherein the first amount of expandable expanded particles is EPS and the second amount of expandable expanded particles is EPLA. 14. The method of claim 13, wherein the EPLA has a crystallinity in the range of 20 to 100%, particularly 30 to 40%. 15. The process according to claim 13 or 14, wherein the EPLA is a copolymer of PLA having a D-content of 2 to 10%, especially 3 to 7%. 16. A method according to any one of claims 1 to 15, wherein the coating is selected from the group consisting of polyurethane, polyvinyl acetate, polyvinyl acetate-based polymers, polyvinyl alcohol, polycaprolactone, polyester, , Polysaccharides, natural waxes or greases and acrylates or a combination of at least one of the foregoing. The method according to claim 16, wherein the amount of coating ranges from 0.5 to 15% by weight, based on the weight of the expandable expanded particles in the second amount in the mixture prepared in step c). 18. The method according to any one of claims 1 to 17, wherein the particle sizes of both the first amount of expandable expanded particles and the second amount of expandable expanded particles are in the range of 0.5 to 5 mm, preferably 0.5 to 3 mm By weight of the foamed molded article. 19. A method according to any one of claims 1 to 18, wherein the pressure is in the range of 0.5 to 30 kg / cm < 2 >. 20. A method according to any one of claims 1 to 19, wherein no additional foaming agent is used in the step of sintering under pressure and heat. An expanded foam obtained after carrying out the process according to any one of claims 1 to 20. 22. The method of claim 21, wherein the composition of the foamed article is based on a sintered physical mixture of a first amount of expandable expanded particles and a second amount of expandable expanded particles, wherein the chemical origin of the first amount of expandable expanded particles is Wherein the coating is present between the first amount of expandable expanded particles and the second amount of expandable expandable particles. 23. The method of claim 21 or 22, wherein said first amount of expandable expanded particles is EPS and said second amount of expandable expanded particles is PLA, wherein PLA is based on the total weight of said foamed article, In the range of 3 to 50% by weight, especially 5 to 20% by weight, more preferably 10 to 15% by weight. Foam molding.

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